/ ˈsedətɪv; NAmE / noun
a drug that makes sb go to sleep or makes them feel calm and relaxed
SYN tranquillizer
► seda·tive adjective [ usually before noun ]:
the sedative effect of the drug
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WORD ORIGIN
late Middle English : from Old French sedatif or medieval Latin sedativus , from Latin sedat- settled, from the verb sedare settle, from sedere sit.